Who fought the most championship heavyweight rounds?

Answer 1

Keith this is one of the toughest questions I've ever answered on here! The first thing you think about is that Joe Louis held the title for almost 12 years, the great Muhammad Ali was 3 time champ and won more decisions than did Joe and Larry Holmes who made a lot of defenses of his title also winning quite a few decisions, so I done some research and here is my answer:

1. Muhammad Ali 265 championship rounds
2. Larry Holmes 242 championship rounds
3. Joe Louis 192 championship rounds

Answer 2

Joe(Brown Bomber)Louis
He held the World Heavyweight Championship for over twelve years.